Just Say `No' To `xeno' Surgery

July 27, 1999|By RAY GREEK and GINA WELCH

Experimenters who hype xenotransplantation -- putting hearts, livers, kidneys and other parts from pigs, baboons, cows, fish and other animals into human bodies -- portray it as making life-saving organs available to people. They shrug off the threat to the human population from species-jumping infectious agents that could trigger worldwide epidemics.

As the U.S. Public Health Service and Food and Drug Administration prepare to issue revised "xeno" guidelines later this year, physicians, the public and politicians alike need to become more outspoken on the issue. In January, the 40-member-nation Council of Europe responsibly voted to ban xenotransplants. The United States and all other countries should do likewise.

As the 1996 "xeno" report from the U.S. National Academy of Science's Institute of Medicine stated, "Because xenotransplants involve the direct insertion of potentially infected (animal) cells, tissues or organs into humans, there is every reason to believe that the potential for transmission of infectious agents (some of which may not even now be recognized) from animals to human transplant recipients is real."

Despite efforts to screen out such agents when breeding animals to be used in xenotransplants, many infectious agents remain hidden. Of course, what scientists do not know exists, they cannot screen for.

"Many viruses lying dormant in animals, in particular herpes viruses and retroviruses, can become activated and deadly in humans," noted the British journal Nature in 1998. A "donor" animal also may have built up a natural immunity to the agent. If that agent is transplanted into a species lacking natural immunity, it can become dangerously infected.

Infectious agents jumping from one species of animals to humans have already caused many outbreaks of disease and epidemics. Different theories surround the origin of AIDS, but most experts believe the disease originated with a chimpanzee virus. Scientists have also linked the huge influenza pandemic of 1918-19 to a pig virus. That "swine influenza" epidemic killed 21 million people worldwide, including 700,000 in the United States. (Actually, at least 25 pig diseases can also infect people.) Rabies, Creutzfeldt-Jakob disease (mad cow disease), and the Ebola virus are other examples of human-affecting diseases that can come from other species.

Luckily, despite being surrounded by infectious bacteria and viruses daily, people usually do not become ill. Natural barriers in our bodies -- our skin, mucous membranes and immune system -- help keep infection at bay. However, because a transplant bypasses most of a patient's usual protective physical and immunological barriers, a xenograft may let known and unknown infectious agents be transmitted to humans.

For someone to accept any transplant, from a human or nonhuman animal, the recipient must receive powerful immunosuppressive drugs to keep the body from rejecting the transplant. While repressing the immune system increases the chance the body will accept an organ, it also increases infection danger. And because the immune system cannot mount a sufficient response to an infection, it is also harder to detect an infection through normal testing. When someone becomes infected from a xenotransplant, that fact might remain unknown until disease symptoms emerge. With a cold or influenza, this generally happens within a couple of days. With a disease such as HIV-AIDS, it may take more than 10 years. By then, who knows how many other people have been infected?

Xenotransplantation makes informed consent impossible. The full range of risks simply are unknown, not only to patients but also to friends, families, co-workers and anyone else coming into contact with patients. Under the 1996 draft "xeno" guidelines, if someone undergoes a xenotransplant and becomes infected with an unknown virus, the person could be quarantined. Others coming into contact with the recipient and becoming infected could also be quarantined.

As Dr. Jonathan Allan, a virologist with the Southwest Foundation for Biomedical Research, states: "It only takes one transplant to start an epidemic."

Fortunately, we have promising alternatives. They include organ-donation-card education programs, artificial organs and well-proven preventive approaches -- such as not smoking, exercising regularly and eating vegetarian -- that will keep us healthier and minimize transplant demand.

The only way to prevent an infectious agent being passed into a human from a xenotransplant is not to perform the operation. There is simply too much risk.

Ray Greek, a retired physician in Springhill, Kan., is a member of the Washington-based Physicians Committee for Responsible Medicine. Gina Welch is a Chicago-area writer. Write to them at: PCRM, 5100 Wisconsin Ave. NW, Suite 404 Washington, DC 20016.